When a tensile stress is applied to concrete that exceeds its tensile capacity then cracking can often occur. This is particularly true for early age concrete which is very vulnerable to cracking due to its low tensile strength. The cracks can be caused by thermal stress, restrained shrinkage and stress induced by movement. Currently knowledge of the properties of early age concrete is limited and further research in this area is required.
With a better understanding of early age concrete, industrial practices could be improved and cracking reduced as structures would not be loaded until the required strength capacity of the concrete is reached. This would also allow a better understanding of when saw-cuts could be made to minimise cracks.
The research undertaken in this Undergraduate Thesis investigates the early age tensile strength of concrete between four to eight hours after casting, under the guidance of Associate Professor P. Dux, Dr P. Morris and Dr M.B. Nooru-Mohamed. Concrete specimens of two slumps, 25mm and 80mm, were tested under varying temperatures and the trends analysed. The results that were achieved will hopefully help to better understand how concrete properties develop throughout the very early stages after casting.